X-Git-Url: https://git.openstreetmap.org./rails.git/blobdiff_plain/34e3e51456774127d43408b7ab65c24f41373f62..4e64291839d45a0c660fc84f11a6c4c811cf8f21:/lib/short_link.rb diff --git a/lib/short_link.rb b/lib/short_link.rb index b09e65f43..ddf37b67a 100644 --- a/lib/short_link.rb +++ b/lib/short_link.rb @@ -5,11 +5,10 @@ # Each character encodes 3 bits of x and 3 of y, so there are extra characters # tacked on the end to make the zoom levels "work". module ShortLink - # array of 64 chars to encode 6 bits. this is almost like base64 encoding, but # the symbolic chars are different, as base64's + and / aren't very # URL-friendly. - ARRAY = ('A'..'Z').to_a + ('a'..'z').to_a + ('0'..'9').to_a + ['_','~'] + ARRAY = ("A".."Z").to_a + ("a".."z").to_a + ("0".."9").to_a + ["_", "~"] ## # Given a string encoding a location, returns the [lon, lat, z] tuple of that @@ -23,7 +22,7 @@ module ShortLink # keep support for old shortlinks which use the @ character, now # replaced by the ~ character because twitter is horribly broken # and we can't have that. - str.gsub!("@","~") + str.gsub!("@", "~") str.each_char do |c| t = ARRAY.index c @@ -31,8 +30,13 @@ module ShortLink z_offset -= 1 else 3.times do - x <<= 1; x = x | 1 unless (t & 32).zero?; t <<= 1 - y <<= 1; y = y | 1 unless (t & 32).zero?; t <<= 1 + x <<= 1 + x |= 1 unless (t & 32).zero? + t <<= 1 + + y <<= 1 + y |= 1 unless (t & 32).zero? + t <<= 1 end z += 3 end @@ -51,11 +55,11 @@ module ShortLink # given a location and zoom, return a short string representing it. def self.encode(lon, lat, z) code = interleave_bits(((lon + 180.0) * 2**32 / 360.0).to_i, - ((lat + 90.0) * 2**32 / 180.0).to_i) + ((lat + 90.0) * 2**32 / 180.0).to_i) str = "" # add eight to the zoom level, which approximates an accuracy of # one pixel in a tile. - ((z + 8)/3.0).ceil.times do |i| + ((z + 8) / 3.0).ceil.times do |i| digit = (code >> (58 - 6 * i)) & 0x3f str << ARRAY[digit] end @@ -64,7 +68,7 @@ module ShortLink # of 3 zoom levels). ((z + 8) % 3).times { str << "-" } - return str + str end private @@ -80,5 +84,4 @@ module ShortLink end c end - end